As the integrated circuit (IC) technologies continue to evolve, packaging requirements will continue to pose challenges. For example, shrinking in process technology, design integration, such as system on a chip, power consumption, and higher pin density may challenge the package design on an IC. A ball grid array (BGA) is an advanced IC package that includes a substrate having conductive contact pads on the bottom for coupling an IC die with a printed circuit board (PCB). A wire bond BGA package includes an IC die having input/output (I/O) pads which are bonded to conductive contact pads on the surface of the substrate by way of wire bonds. In contrast, a flip chip BGA package includes an IC die having I/O pads which are directly bonded to the substrate using solder bumps. Unlike in a wire bond BGA package, the IC die having the solder bumps is flipped over and placed face down in a flip chip BGA package, with the solder bumps connecting directly to corresponding conductive contact pads on the top surface of the substrate. The contact pads on the bottom of the substrate of either type of package may be soldered to a PCB of a system.
Flip chip packages are particularly useful with ICs having a large number of pins, such as programmable logic devices (PLDs). A PLD is an IC designed to be programmed or configured by a user so that the user may implement any design of their choice. One type of PLD is a field programmable gate array (FPGA). In a typical FPGA, an array of configurable logic blocks (CLBs) is coupled to programmable input/output blocks (IOBs). The CLBs and IOBs are interconnected by a hierarchy of programmable routing resources. These CLBs, IOBs, and programmable routing resources are customized by loading a configuration bitstream, typically from off-chip memory, into configuration memory cells of the FPGA.
However, as the density, complexity, and the amount of circuitry for a given IC continues to increase, the noise associated with such IC continues to increase. Also, such ICs are being utilized in many applications that require multiple I/O standards support, which may require additional passive components, such as capacitors and resistors to meet such standards. These requirements are a particular problem in a PLD due to the switching noise of digital circuits, high density of interconnect lines, and the high package pin count. For instance, in order for the circuit to operate properly, it is important to effectively control noise generated internally from digital switching. One way to control such noise is through the use of decoupling capacitors. In an example, the IC package 100 of FIG. 1 may include discrete elements, such as capacitors, 106 and 108 coupled to power terminals of the IC die 104. The discrete elements 106 and 108 may suppress noise coupled to the supply terminals due to switching logic.
In one example, the IC package 100 of FIG. 1 may include openings or relief openings 105 on the substrate. The relief openings 105 may be positioned in various locations on the substrate to improve the overall quality of the IC package. For instance, the openings may aid in the relief of stresses, such as environmental fluctuations including temperature changes due to the assembly process and the operation of the IC in a system. A disadvantage of having the relief openings 105 is the allowance of solutions, such as solvents and moisture, to penetrate the IC package during the assembly process of a system and/or normal operation of the IC. The presence of solutions may degrade the quality of the IC package, and therefore, the performance of the IC. For instance, the prolonged exposure to the solutions may corrode terminals of the components 106 and 108. The corroded terminals of the components may increase the contact resistance between the substrate and a terminal of the component, therefore, reducing the effectiveness of the component, and therefore, degrading performance of the IC. In other instances, the corrosion may sever the electrical connection (e.g., very high impedance) between the substrate and the terminal of the component. In such instances, the IC may fail to operate properly.
Therefore, there is a need for an improved method and implementation of discrete component on a substrate of an IC package, such as a discrete capacitor or resistor that meets performance and quality criteria of the IC design.